Not Applicable.
The present invention generally relates to a cleaning composition for hard surfaces. More particularly, the invention relates to a novel hard surface cleaning formulation having superior cleaning ability which is free of VOC-containing solvents.
General purpose household cleaning compositions for hard surfaces such as metal, glass, ceramic, plastic and linoleum surfaces are commercially available in both powdered and liquid form. Powdered cleaning compositions consist mainly of builder or buffering salts such as phosphates, carbonates, and silicates and although such compositions may display good inorganic soil removal, they exhibit inferior cleaning performance on organic soils such as greasy/fatty/oily soils.
Liquid cleaning compositions, on the other hand, have the great advantage that they can be applied to hard surfaces in neat or concentrated form so that a relatively high level of surfactant material is delivered directly to the soil. Moreover, it is a rather more straightforward task to incorporate high concentrations of anionic or nonionic surfactant in a liquid rather than a granular composition. For both of these reasons, therefore, liquid cleaning compositions have the potential to provide superior grease and oily soil removal over powdered cleaning compositions.
Nevertheless, liquid cleaning compositions suffer a number of drawbacks which can limit their consumer acceptability. Thus, they generally contain little or no detergency builder salts and consequently they tend to have poor cleaning performance on particulate soil and also lack effectiveness under varying water hardness levels. In addition, they can suffer problems relating to homogeneity, clarity, and viscosity when used by consumers. Moreover, the higher in-use surfactant concentration necessary for improved grease soil removal causes further problems relating to extensive suds formation requiring frequent rinsing and wiping on behalf of the consumer.
A solution to the above-identified problems has involved the use of saturated and unsaturated terpenes, in combination with a polar solvent, in order to increase the cleaning effectiveness of the hard surface cleaner and control sudsing. A problem associated with the use of terpenes such as, for example, d-limonene, is that their price, as a raw material, tends to fluctuate wildly. Consequently, the cost to manufacture hard surface liquid cleaners containing terpene solvents is financially disadvantageous to both producers and consumers.
Other solvents which are often employed in hard surface cleaning compositions, instead of terpenes, include those derived from aliphatic, aromatic and halogenated hydrocarbons. Their use, however, is undesirable for environmental reasons due to the presence of volatile organic compounds (VOC""s) therein.
Consequently, it would be highly desirable to employ a solvent which is both free of volatile organic compounds and is not subject to any significant fluctuations in pricing for the raw material.
One approach to overcoming the above limitations is a terpene-free hard surface cleaning composition which is a microemulsion comprised of a nonionic surfactant, an anionic surfactant; a primary solvent consisting of a C6-C22 methyl ester; a short-chain cosurfactant; and water as described in copending application Ser. No. 08/954,012, filed on Oct. 20, 1997. Such microemulsions exhibit limited high and low temperature stability. Therefore, an object of the present invention is a microemulsion containing a C1-C4 alkyl ester of a C6-C22 saturated or unsaturated carboxylic acid having improved high and low temperature stability as evidenced by being clear and homogeneous over a temperature range broader than that previously achieved with similar microemulsions.
One aspect of the present invention pertains to a terpene-free hard surface cleaning composition comprised of a C1-C4 alkyl ester of a C6-C22 saturated or unsaturated carboxylic acid and a surfactant having an HLB of from about 4 to about 10.
Another aspect of the present invention pertains to a terpene-free hard surface cleaning composition which is a microemulsion having improved high and low temperature stability comprised of an anionic surfactant; a primary solvent consisting of a C1-C4 alkyl ester of a C6-C22 saturated or unsaturated carboxylic acid and a short-chain cosurfactant. The present invention is also directed to a process for cleaning a hard surface involving contacting the hard surface with one of the above-disclosed cleaning compositions over a predetermined length of time.